According to Lövdén et al. (2010, Psychological Bulletin), adult cognitive plasticity, or the brain’s capacity for anatomically implementing reactive changes in the range of performance, is driven by a prolonged mismatch between functional organismic supplies and environmental demands, and may alter processing efficiency or representations. Based on this framework, I will evaluate the available evidence on cognitive plasticity in adulthood and old age, recommend design features for cognitive-training studies, and outline future research questions.